The present invention relates to an antenna mounting structure for mounting an antenna base to a roof panel or the like of a vehicle body.
In a conventional structure for mounting an antenna device for a vehicle to a roof panel of a vehicle body, a mount screw protruded downward from an antenna base of the antenna device is inserted through a mount hole formed on the roof panel, and a washer having a daw is fitted and inserted from below into the mount screw protruded downward from the roof panel, and furthermore, a nut is screwed and fixed.
In order to enhance a workability, the washer having a claw and the nut are coupled and integrated so as to be relatively rotatable around a screw axis and not to be separated from each other in the direction of the screw axis. In order to further enhance the workability, Japanese Patent No. 2751146 teaches a structure capable of provisionally fixing a nut to a mount screw through a washer having a claw and preventing the nut from slipping from the mount screw after the provisional fixation even if an operator releases his or her hand from the nut. In this structure, a slit is formed on the mount screw so as to extend in the direction of the screw axis and the washer is provided with a fitting piece to be elastically deformed and press-fitted into the slit. The nut is coupled to the washer.
In this structure, if the width of the slit or fitting piece to be provided on the mount screw has a dimensional variation in a manufacture, however, there is an anxiety that the press-fitting for the provisional fixation might not be carried out or an elastic force for holding the nut on the mount screw by the provisional fixation might be reduced to cause the nut to slip off. Therefore, it is necessary to carry out the manufacture by setting the widths of the slit of the mount screw and the fitting piece of the washer with high dimensional precision.
In order to solve the above problem, there is proposed a related-art structure shown in FIGS. 7A through 9B.
As shown in FIGS. 7A and 7B, a mount screw 12 is protruded downward from an antenna base 10. The mount screw 12 is provided with a slit 14 extending in the direction of a screw axis from a lower surface thereof. An engaging plate 16 shown in FIG. 8 is fixed to the lower end face of the mount screw 12 by caulking or the like. The engaging plate 16 is formed by a resin plate in which a cutout 18 and elastic pieces 20 protruded from edges of the cutout 18. The pieces 20 are configured to be elastically deformed in the direction of the screw axis. As shown in FIGS. 9A and 9B, a washer 22 is provided with an engaging piece 24. When the washer 22 is fitted with the mount screw 12, the engaging piece 24 is inserted into the slit 14 while deforming the elastic pieces 20. After the fitting, the engaging piece 24 is prevented from moving downward by the elastic pieces 20 to establish a provisional fixation. The washer 22 is provided with claws 28 to cut into a roof panel 26 of a vehicle to carry out an electrical connection. A nut 30 is coupled to the washer 22 so as to be relatively rotatable around the screw axis and not to be separated from each other in the direction of the screw axis.
A holder 32 formed of a resin having elasticity is fixed integrally with the antenna base 10 by caulking or the like. The holder 32 is formed with elastic holder arms 35 having, on tip portions thereof, hooks 34 directed outward. By inserting the holder 32 into a mount hole 36 provided on the roof panel 26 such that the hooks 34 engage with the edge of the mount hole 36, the antenna device is prevented from being slipped off. A rubber base 38 serving as a sealing member is provided between the antenna 10 and the roof panel 26. Moreover, the elastic pieces 20 of the engaging plate 16 are configured such that they are not elastically deformed by the weights of the washer 22 and the nut 30 and the washer 22 is prevented from slipping off by only a weight. A housing 40 is formed integrally with the antenna base 10 by insert molding. An antenna element 42 is pivotably fixed to the housing 40.
Even if an operator releases his or her hand in the provisional fixing state, the nut 30 does not slip downward so that a workability can be improved. Moreover, a force for provisionally fixing and holding the nut 30 is generated because the elastic pieces 20 of the engaging plate 16 are not elastically deformed by only the weights of the washer 22 and the nut 30, and is not greatly influenced by dimensional precision. For this reason, a member requiring the dimensional precision is not provided so that the manufacturing cost can be reduced.
However, since there is a great play between the nut 30 and the mount screw 12 when the provisional fixation is established, it is sometimes difficult to align the axes of the nut 30 and the mount screw 12 when the nut 30 is screwed on the mount screw 12, thereby lowering the workability. Further, in a case where a force or impact in the direction perpendicular to the direction of the screw axis is applied, the engaging piece 24 is easily slipped off from the slit 14, so that the nut 30 is shifted from the proper position relative to the mount screw 12.